Was there any other text after the "B Register C:", which may be hidden due to a narrow column in the gui?
I have DivX but I run with an old (more reliable for me) version of the Web Player which for whatever reason hasn't generated a similar entry in my startup.
I appreciate that "B Register C:" on it's own could refer to anything but a lot of research has come up with absolutely nothing but the DivX reference.
I wouldn't worry about that entry Dan if you have DivX installed as it's more than likely related to that install.
You didn't say how long you've been aware of it, but if whatever it is has been disabled for any length of time, and everything is fine with your computer and DivX in particular I would just leave it as is.
You could delete it, but being disabled is the next best thing and the fact that you will have the option to enable it again sometime if needed (probably never) could be a comfort.
And of course being disabled it can't do anything except sit there and annoy you ... if you let it.
I have a few entries I could safely delete as they've been disabled for a long time, but I just leave them there and forget them.
Hope that helps Dan as DivX is the only hit I've had after quite a few different search attempts with varying search parameters.